1. Field of the Invention
This invention relates to an oil burner of the type of pumping up a fuel oil such as kerosene, and more particularly to an oil burner capable of allowing the flow rate of an air and the supply rate of a fuel oil to be proportionally controlled with respect to each other.
2. Description of the Prior Arts
In an oil burner of the type of controlling the flow rate of an air and the supply rate of a fuel oil to be supplied to a combustion means, an oil level setting means is airtightly constructed and is communicated at the upper space portion thereof through a ramification pipe to an air duct for supplying an air to the combustion means, so that the supply rate of a fuel oil is controlled proportionally to the flow rate of an air. Such conventional oil burner is disclosed in Japanese Utility Model Publication No. 30309/69. However, such conventional oil burner is constructed to directly set the level of a fuel oil in an oil level setting means by the pressure of an air forced by a fan with respect to the position of a combustion means. Thus, when a fan of the type of supplying a large amount of air under a low pressure such as a multiblade fan is incorporated in such conventional oil burner, it has been required to keep the surface of a fuel oil in an oil level setting means at a high level with respect to a combustion means; and further, in view of the flow resistance of a fuel oil, it has been required to set the level of a fuel oil at a very high position with respect to a combustion means. However, such construction has a disadvantage of often causing a fuel oil to spill in a combustion means when tilting an oil burner at the time of, for example, moving it. When a fuel oil spills in a combustion means, it becomes impossible to burn a fuel oil unless the spilt oil is completely gasificated during a process of preheating a fuel oil; because the fuel oil supplied to the combustion means does not reach a temperature sufficient to be burned. Further, the gasification of the spilt oil causes an offensive odor to be emitted. Accordingly, it is generally required to disassemble an oil burner to wipe up the spilt oil. In order to avoid such trouble, it has been required to provide a pipe for supplying a fuel oil from an oil level setting means to a combustion means with an on-off valve, this resulting in the construction and operation of an oil burner being complicated. In addition, such construction has a further disadvantage that the on-off valve remains open where it is choked with foreign substances such as a dust and the like contained in a fuel oil, to thereby prevent the normal operation of an oil burner.
While, when a fan of the type of supplying a small amount of air under a high pressure such as a turbofan is incorporated in such conventional oil burner as mentioned above, it is possible to obtain a pressure sufficient to forcedly supply a fuel oil to a combustion means even if the level of a fuel oil in an oil level setting means is set at a low position with respect to the combustion means, to thereby prevent the spill of a fuel oil in the combustion means as mentioned above without providing an oil supply pipe with an on-off valve. However, such fan of supplying a small amount of air under a high pressure has a disadvantage of generating a loud noise as encountered with an electric cleaner and the like. Further, such fan has an additional disadvantage of making the control of flow rate of an air difficult due to the fact that an air is supplied under a high pressure, so that it has been difficult to obtain the optimum balance between the flow rate of an air and the supply rate of a fuel oil. In order to obtain the optimum balance, it is required to use an oil level setting means constructed to prevent the leakage of an air under a high pressure, this resulting in the manufacturing costs for an oil burner being increased. In addition, an oil burner incorporating such fan therein is generally adapted to restrict the supply rate of a fuel oil by greatly restricting the flow rate of an air, however, this results in the lack of an air in a slight combustion. In order to prevent the incomplete combustion, it is required to supply an air to a combustion means by means of a by-pass line, to thereby control the overall flow rate of an air; however, such construction requires to finely control the flow rate of an air and the supply rate of a fuel oil by means of an airtight damper of a high precision provided in the by-pass line, to thereby cause the manufacturing costs for an oil burner to be increased as well to cause the construction to be complicated.
Further, there has been also used an oil burner of the type of simultaneously controlling the flow rate of an air and the supply rate of a fuel oil. Such additional prior art oil burner is constructed in such a manner that a means for adjusting the supply rate of a fuel oil is airtightly constructed and is adapted to receive a pressure generated in a combustion chamber so as to supply a suitable amount of fuel oil to the combustion chamber in accordance with the variation in pressure in the combustion chamber caused due to the variation in air pressure applied on the top portion of an exhaust cylinder, to thereby prevent an abnormal combustion. However, as an airtight means for adjusting the supply rate of a fuel oil to be used in such conventional oil burner, it has been impossible to use an adjusting means of a type other than a floating type.